The present invention relates to electrical circuitry, and more particularly, but not exclusively, relates to interface circuits including a transistor.
The ongoing desire for faster circuitry with fewer components has fueled a need for better ways to interface various circuits and circuitry components. Improved interfacing for electro-optical devices, such as photodetectors and laser generating components, is of particular interest. Proposed interface circuits for certain photodectors typically limit the available frequency response and/or signal-to-noise ratio of such devices. In other proposed arrangements, interfaces between certain laser generating components and one or more corresponding input signal sources often include complicated filter networks in an attempt to provide adequate impedance matching. Besides electro-optics, other applications would also benefit from better interfacing. Thus, there is a demand for further advancement in this area of technology.
As used herein, xe2x80x9ctransistor devicexe2x80x9d broadly refers not only to a single transistor, but also to a transistor combined with one or more other electronic elements to provide an active device that includes at least three terminals. By way of nonlimiting example, transistor device includes multiple transistor combinations, such as two or more transistors connected in parallel, the Darlington configuration, and the Sziklai configuration, to name a few; or different configurations including at least one transistor as would occur to one skilled in the art. Further, as used herein, xe2x80x9ctransistorxe2x80x9d broadly refers to any transistor type, including, but not limited to, a Bipolar Junction Transistor (BJT), Junction Field Effect Transistor (JFET), Insulated Gate Field Effect Transistor (IGFET) (where IGFETs include Metal Oxide Semiconductor Field Effect Transistor (MOSFET) types). Also as used herein, xe2x80x9ccommon basexe2x80x9d or xe2x80x9ccommon gatexe2x80x9d refers to a transistor device for which input and output signals of interest are each associated with a transistor device terminal other than a base or gate.
One embodiment of the present invention includes a unique interface circuit. Other embodiments include unique circuits, systems, devices, apparatus, and methods for interface circuitry.
In a further embodiment, interface circuitry includes a transistor device in a common base or common gate configuration. This configuration can include a servo device that receives feedback from one terminal of the transistor device to maintain a relatively constant level at that terminal.
Still a further embodiment of the present invention includes a transistor device in a common base or common gate configuration that amplifies an input signal from a photodetector. A transistor emitter is coupled to the photodetector to receive the input signal and an output is provided from a transistor collector. An operational amplifier can be included with an output operable to drive a transistor base and a negative input coupled to the transistor emitter.
Yet another embodiment of the present invention includes: controlling operation of a transistor device in a common base or gate mode with a servo device; providing negative feedback from a first terminal of the transistor device to a first input of the servo device; providing a selected voltage level to a second input of the servo device; and biasing another device coupled to the first terminal in accordance with the selected voltage level.
Another embodiment of the present invention includes: operating a transistor device in a common base or gate configuration; coupling two or more input signal pathways to the transistor device; and providing an output to another device from the transistor device. In one form, this other device is of a laser-generating type.
For another embodiment, a transistor device includes an emitter, a base, and a collector, that is arranged in a common base configuration to maintain the emitter at a predefined voltage. A number of input signal pathways are coupled to the emitter and a current-dependent load is coupled to the collector. This load is responsive to an input signal received through one of the input signal pathways.
Circuitry of a further embodiment of the present invention includes a transistor device operated in a common base or gate configuration to provide a virtual ground at a first terminal, and a laser device electrically coupled to a second terminal of the transistor device. Operation of the laser device is controlled with one or more input signals provided to the first terminal of the transistor.
Yet a further embodiment of the present invention includes: controlling a common base or common gate mode of operation of a transistor device with a servo device, where the servo device provides an output to the transistor device and receives feedback from the transistor device; applying an approximately constant bias current to the transistor device with a current source; receiving an input signal at an electrical node between a first terminal of the transistor device and the current source; and providing an output signal from the transistor device.
One object of the present invention is to provide a unique interface circuit.
Another object of the present invention is to provide a unique interface circuit, system, device, apparatus, or method.
Further objects, embodiments, forms, features, advantages, benefits, and aspects of the present invention shall become apparent from the detailed description and drawings provided herewith.